補充上一篇
利用Arraylist實現的堆排序(包含升序和降序)

import java.util.ArrayList;
import java.util.Random;

//採用Arraylist實現堆排序
public class Main {
    //為了方便 採用索引從 1 開始
    private static int N = 10;// 陣列的大小
    static Random rand = new Random();

    public static void main(String[] args) {
        // TODO Auto-generated method stub
 

        test_HeapSort_DES();
        test_HeapSort_ASC();
    }

    private static void test_HeapSort_DES() {
        // TODO Auto-generated method stub
        ArrayList<Integer> arrayList=new ArrayList<>();
        arrayList.add(-1);
        for (int i = 1; i <= N; i++) {
            arrayList.add(rand.nextInt(1000
 
));
        }
        System.out.println("排序前：");
        print(arrayList);       

        System.out.println("排序後(降序)：");
        print(HeapSort_DES(arrayList));

    }
    private static void test_HeapSort_ASC() {
        // TODO Auto-generated method stub
        ArrayList<Integer> arrayList=new
 
 ArrayList<>();
        arrayList.add(-1);
        for (int i = 1; i <= N; i++) {
            arrayList.add(rand.nextInt(1000));
        }
        System.out.println("排序前：");
        print(arrayList);       

        System.out.println("排序後(升序)：");
        print(HeapSort_ASC(arrayList));

    }

    private static ArrayList<Integer> HeapSort_ASC(ArrayList<Integer> arrayList) {
        // TODO Auto-generated method stub
        Build_Max_Heap(arrayList);
        ArrayList<Integer> temp=new ArrayList<>();
        temp.add(-1);//方便列印
        while(arrayList.size()>1){
            temp.add(1,arrayList.get(1));//與逆序的差別 每次插在第一個
            arrayList.remove(1);
            Max_Heapfy(arrayList,1);
        }
        return temp;
    }

    private static ArrayList<Integer> HeapSort_DES(ArrayList<Integer> arrayList) {
        // TODO Auto-generated method stub
        Build_Max_Heap(arrayList);
        ArrayList<Integer> temp=new ArrayList<>();
        temp.add(-1);//方便列印
        while(arrayList.size()>1){
            temp.add(arrayList.get(1));
            arrayList.remove(1);
            Max_Heapfy(arrayList,1);
        }
        return temp;

    }

    private static void Build_Max_Heap(ArrayList<Integer> arrayList) {
        // TODO Auto-generated method stub
        int length=arrayList.size()-1;
        for(int i=length/2;i>0;i--){
            Max_Heapfy(arrayList, i);
        }
    }

    private static void Max_Heapfy(ArrayList<Integer> arrayList, int i) {
        // TODO Auto-generated method stub
        if(arrayList.size()<=1)
            return;
        int l=left(i);
        int r=right(i);
        int largest=0;
        if(l<arrayList.size() && arrayList.get(l)>arrayList.get(i)){
            largest=l;
        }else{
            largest=i;
        }
        if(r<arrayList.size() && arrayList.get(r)> arrayList.get(largest)){
            largest=r;
        }
        if(largest!=i){
            int temp =  arrayList.get(i);
            arrayList.set(i, arrayList.get(largest));
            arrayList.set(largest, temp);       
            Max_Heapfy(arrayList,largest);
        }       
    }

    private static int right(int i) {
        // TODO Auto-generated method stub
        return 2*i+1;
    }

    private static int left(int i) {
        // TODO Auto-generated method stub
        return 2*i;
    }

    //列印
    private static void print(ArrayList<Integer> arrayList) {
        // TODO Auto-generated method stub
        for(int i=1;i<arrayList.size();i++){
            System.out.print(arrayList.get(i)+"\t");
        }
        System.out.println();
    }
}

結果截圖